The present invention relates to novel derivatives of benzoic acid esters, to their use in particular in cosmetics, and to the compositions containing them.
Inhuman beings, the growth of hair and its renewal are mainly determined by the activity of the hair follicles and their dermoepidermal environment. Their activity is cyclic and comprises essentially three phases, namely the anagen phase, the catagen phase and the telogen phase.
The anagen phase or growth phase, which lasts for several years and during which the hair grows longer, is followed by a very short and transitory catagen phase which lasts for a few weeks, and then by a resting phase, called the telogen phase, which lasts for a few months.
At the end of the resting period, the hair falls out and another cycle begins. The hair is therefore continuously renewed, and of the approximately 150,000 hair strands which make up the hair, at each instant, approximately 10% of them are in the resting phase and will therefore be replaced in a few months.
In a large number of cases, the premature loss of the hair occurs in genetically predisposed subjects and it affects men in particular. It involves more particularly androgenetic or androgenic or alternatively androgeno-genetic alopecia.
This alopecia is essentially due to a disruption in hair renewal which causes, in the first instance, the acceleration of the frequency of the cycles at the expense of the quality of the hair and then of its quantity. A gradual deterioration of the hair is brought about by regression of the so-called  less than  less than terminals greater than  greater than  hair at the down stage. Some areas are preferably affected, in particular the temporal or frontal sinuses and the upper part of the occipital in men, whereas in women a diffuse alopecia of the vertex is mainly observed.
Substances which make it possible to suppress or reduce the effect of alopecia, and in particular to induce or stimulate growth of head hair and/or body hair, or even to reduce its loss, have been sought for many years, in particular in the cosmetics industry. For this purpose, a large number of widely varying active substances have indeed already been proposed, such as for example 2,4-diamino-6-piperidinopyrimidine 3-oxide or  less than  less than Minoxidil greater than  greater than  described in U.S. Pat. No. 4,596,812 or its many derivatives such as those described for example in patent applications EP 353123, EP 356271, EP 408442, EP 522964, EP 420707, EP 459890 and EP 519819. There may also be mentioned 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidinopyrimidine and its derivatives, which are described more particularly in patent U.S. Pat. No. 4,139,619.
The fact remains, in general, that it would be advantageous and useful to be able to have active compounds other than those already known, which are preferably potentially more active and/or less toxic, and which can be used in the cosmetic field.
However, after many research studies, the Applicant has just demonstrated that novel compounds, derived from benzoic acid esters, exhibit remarkable properties which may justify their use for reducing and/or slowing down the loss of head hair and/or body hair. These compounds could also be potentially capable of inducing and/or stimulating its growth.
Thus, the subject of the invention is novel compounds corresponding to the following formula (I): 
in which:
R1 represents:
a linear or branched C1-C12 aliphatic alkyl group, optionally substituted with one or more groups chosen from OH, NH2, SH; CONHR5, COOR5, OR5, SR5, SiOR5, NHR5 in which R5 is a linear or branched C1-C4 alkyl radical; CN, CF3, halogen, or with one or more aliphatic or aromatic, optionally heterocyclic, C3-C6 rings;
an aryl group, optionally substituted with one or more groups OH, NH2, SH, COOH; CONHR6, COOR6, OR6, SR6, NHR6 in which R6 is a linear or branched C1-C12 alkyl radical; CN, CF3, halogen, or with one or more aliphatic or aromatic, optionally heterocyclic, C3-C6 rings; or
a natural or synthetic polymer or copolymer carrying one or more combinations of the following groups: hydroxyl, carboxylate, primary amine, secondary amine, tertiary amine, thiol, aldehyde.
R2 represents a hydrogen or halogen atom, a radical CN, CF3, OH, OCF3, COOH, R7, OR7 or OCOR7 in which R7 denotes a linear or branched C1-C4 aliphatic alkyl radical.
R3 represents a mono- or polyhalogenated linear or branched C1-C4 alkyl radical, or an aryl radical, optionally substituted with one or more groups chosen from OH, NH2, SH, CN, CF3, halogen, COOH, CONHR8, COOR8, OR8, SR8, NHR8 in which R8 is a linear or branched C1-C12 alkyl radical.
R4 represents a linear or branched C1-C4 alkyl radical, optionally substituted with a halogen atom, or represents a CF3 radical.
The subject of the invention is also a composition, in particular a cosmetic composition, comprising, in a physiologically acceptable medium, at least one compound as defined above.
The subject of the invention is also the use, in particular in a composition, in particular a cosmetic composition, or for the preparation of a physiologically acceptable composition, of at least one compound corresponding to formula (I) for reducing and/or slowing down the loss of head hair and/or body hair, or even inducing and/or stimulating its growth.
One of the advantages of the invention consists in the fact that the compounds according to the invention are free of side effects since they are metabolized into an acid which is free of anti-androgen effect.
The compounds according to the invention are represented by the following formula (I): 
in which:
R1 represents:
a linear or branched C1-C12 aliphatic alkyl group, optionally substituted with one or more groups chosen from OH, NH2, SH; CONHR5, COOR5, OR5, SR5, SiOR5, NHR5 in which R5 is a linear or branched C1-C4 alkyl radical; CN, CF3, halogen, or with one or more aliphatic or aromatic, optionally heterocyclic, C3-C6 rings;
an aryl group, optionally substituted with one or more groups OH, NH2, SH, COOH; CONHR6, COOR6, OR6, SR6, NHR6 in which R6 is a linear or branched C1-C12 alkyl radical; CN, CF3, halogen, or with one or more aliphatic or aromatic, optionally heterocyclic, C3-C6 rings; or
a natural or synthetic polymer or copolymer carrying one or more combinations of the following groups: hydroxyl, carboxylate, primary amine, secondary amine, tertiary amine, thiol, aldehyde.
R2 represents a hydrogen or halogen atom, a radical CN, CF3, OH, OCF3, COOH, R7, OR7 or OCOR7 in which R7 denotes a linear or branched C1-C4 aliphatic alkyl radical.
R3 represents a mono- or polyhalogenated linear or branched C1-C4 alkyl radical, or an aryl radical, optionally substituted with one or more groups chosen from OH, NH2, SH, CN, CF3, halogen, COOH, CONHR8, COOR8, OR8, SR8, NHR8 in which R8 is a linear or branched C1-C12 alkyl radical.
R4 represents a linear or branched C1-C4 alkyl radical, optionally substituted with a halogen atom, or represents a CF3 radical.
Among the natural polymers which may be to represent R1, there may be mentioned modified natural polymers such as ether or ester derivatives of cellulose, polysaccharides, oligosaccharides and glycosaminoglucans.
Preferably, R1 represents an optionally substituted aryl group, and in particular a phenyl or benzyl group.
Preferably, R2 represents a hydrogen atom, a halogen atom and in particular a chlorine atom, or a hydroxyl radical.
Preferably, R3 represents a halogenated, in particular fluorinated, alkyl radical, or a phenyl radical. In particular, R3 may represent the CF3 radical.
Preferably, R4 represents a methyl radical.
Among the compounds of formula (I), there may be more particularly mentioned:
4-(O-methyloxime)phenyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
phenyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
methyl ester of 4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
para-tolyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
phenyl ester of 2-hydroxy-4-(2-phenyl-2-hydroxypropionylamino)benzoic acid;
methyl ester of 2-methoxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
phenyl ester of 2-chloro-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
methyl ester of 2-ethyl-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
3,5-bis(trifluoromethyl)benzyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
tert-butyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
3-morpholinopropyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid;
4-octylphenyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid; and
methyl ester of 2-hydroxy-4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionylamino)benzoic acid.
The compounds of formula (I) may be used alone or in the form of a mixture.
The quantity of compound to be used in the compositions according to the invention can be easily determined by persons skilled in the art according to the nature of the compound used, the person to be treated and/or the desired effect. In general, this quantity may be between 0.0001 and 30% by weight relative to the total weight of the composition, in particular between 0.01 and 10% by weight, and preferably between 0.1 and 5% by weight.
Thus, the compounds of formula (I) according to the invention may in particular be used in a composition or for the preparation of a composition which comprises, moreover, a physiologically acceptable medium.
This composition may be provided in the form of a cosmetic composition which therefore comprises a cosmetically acceptable medium.
The physiologically acceptable medium in which the compounds according to the invention may be used can be easily determined by persons skilled in the art.
In general, it may be anhydrous or aqueous.
The expression anhydrous medium is understood to mean a solvent medium containing less than 1% by weight of water. This medium may consist of an organic. solvent or of a mixture of organic solvents chosen more particularly from C1-C4 alcohols such as ethanol; alkylene glycols such as propylene glycol; alkyl ethers of alkylene glycols or of dialkylene glycols, in which the alkyl or alkylene radicals contain from 1 to 4 carbon atoms.
The expression aqueous medium is understood to mean a medium consisting of water or of a mixture of water and of another physiologically acceptable solvent, chosen in particular from the organic solvents mentioned above. In the latter case, these other solvents may represent about 5 to 95% by weight of the composition.
It is possible to add to the composition, in combination with the compounds of the invention, one or more compounds which further enhance the activity on hair regrowth and/or on slowing down hair loss, and which have already been described for this activity.
There may be mentioned more particularly, without limitation:
nicotinic acid esters, including in particular tocopherol nicotinate, benzyl nicotinate and C1-C6 alkyl nicotinates such as methyl or hexyl nicotinates;
pyrimidine derivatives, such as 2,4-diamino-6-piperidinopyrimidine 3-oxide or  less than  less than Minoxidil greater than  greater than  described in patents U.S. Pat. Nos. 4,139,619 and 4,596,812;
agents promoting hair regrowth such as those described in patent application EP0648488;
antibacterial agents such as macrolides, pyranosides and tetracyclines, and in particular erythromycin;
calcium-antagonizing agents such as cinnarizin, diltiazem, nimodipine and nifedipine;
hormones such as estriol and its analogs, or thyroxin and its salts;
steroidal or nonsteroidal anti-inflammatory agents, such as corticosteroids (for example: hydrocortisone);
antiandrogenic agents such as oxendolone, spironolactone, diethylstilbestrol and flutamide;
steroidal or nonsteroidal inhibitors of 5-xcex1-reductases such as finasteride;
potassium agonists such as cromakalim and nicorandil;
agonists of retinoid RXR receptors and antagonists of retinoids;
scavengers of OH radicals, such as dimethyl sulfoxide;
peptides such as for example the tripeptide Lys-Pro-Val, and more generally xcex1-MSH and its derivatives.
The following compounds may also be added to this list:
diazoxide, spiroxasone,
phospholipids such as lecithin,
linoleic and linolenic acids,
salicylic acid and its derivatives described in French patent FR 2 581 542, such as their salicylic acid derivatives carrying an alkanoyl group having from 2 to 12 carbon atoms at the 5-position of the benzene ring,
hydroxycarboxylic or ketocarboxylic acids and their esters,
lactones and their corresponding salts,
anthralin, carotenoids,
eicosatetraenoic and eicosatrienoic acids or their esters and amides,
vitamin D and its derivatives,
extracts of plant or bacteria origin.
Moreover, there may be added, to the physiologically acceptable medium, adjuvants normally used in the field of application considered, in particular in the cosmetic field, such as surfactants, thickening or gelling agents, cosmetic agents, preservatives, alkalinizing or acidifying agents well known in the state of the art.
The nature and the quantity of these adjuvants may be chosen by persons skilled in the art on the basis of their general knowledge so as to obtain the form of presentation desired for the composition. In any case, persons skilled in the art will be careful to choose all the possible additional compounds and/or their quantity so that the advantageous properties of the composition according to the invention are not, or not substantially, impaired by the addition envisaged.
The compositions according to the invention may be provided in the form of a lotion which is thickened to a greater or lesser degree, a gel, an emulsion or a cream. They may be optionally used in pressurized form as an aerosol or as a spray from a pump dispenser.
The compositions may also be provided in liposomal form, as described in particular in patent application WO 94/22468. In this case, the compound encapsulated in the liposomes may be selectively delivered to the hair follicles.
The compositions according to the invention may be applied to the alopecic areas of the scalp and/or of the head hair and/or of the body hair of one individual, and may then be optionally left in contact for several hours and may be optionally rinsed off.
It is possible, for example, to apply the composition comprising an effective quantity of a compound according to the invention to the hair or the scalp in the evening, to keep it in contact overnight and to optionally shampoo in the morning. These applications may be repeated daily for one or more months according to the individual.
Thus, the subject of the present invention is also a method for the cosmetic treatment of head hair, body hair and/or the scalp, in which a cosmetic composition comprising an effective quantity of at least one compound of formula (I) is applied to the head hair, the body hair and/or the scalp, leaving it in contact with the head hair and/or the scalp and/or the body hair, and optionally rinsing off.
The method of treatment exhibits the characteristics of a cosmetic method insofar as it makes it possible to improve the esthetic appearance of the hair by giving it greater vitality and improved appearance.
The invention is illustrated in greater detail in the following examples.